An image data input/output system which is connected to a network, applies image data processing to external or internal image data, and outputs the processed image data, is known.
As this image data input/output system, a so-called MFP (Multi Function Peripheral) is available.
FIG. 2 shows a controller 100 for controlling the conventional MFP. In the controller 100, a CPU 102, memory controller (MC) 103, general-purpose bus 105, image processing unit 112, and image data rasterization unit (RIP (Raster Image Processor)) 115 are connected via a system bus bridge (SBB) 101.
To the general-purpose bus 105, a hard disk controller (HDDCont) 106 for controlling an HDD (hard disk drive) 107 used to store image data, and a console controller 108 for controlling a console (e.g., a touch panel comprising an LCD and the like) 109 are connected. Furthermore, to the general-purpose bus 105, a network I/F 110 which serves as an interface for transferring image data with an external device via a network 111, to which the MFP is connected, is connected. As this image data, image data of a page vector format (PDL (page description language), PDF, SVG, and the like) is used.
To the HDDCont 106, the HDD (hard disk drive) 107 is connected and is used as a storage medium of image data. Likewise, to the MC 103, a system memory (Memory) 104 is connected and is used as a medium for temporarily storing image data. As the system memory 104, a DIMM is normally used.
To the image processing unit 112, a scanner 113 and printer 114 are connected. Image data input from the scanner 113 undergoes predetermined image processing by the image processing unit 112, and is then input to the controller 100. Image data stored in the controller 100 undergoes predetermined image processing by the image processing unit 112, and is output to the printer 114.
Upon handling image data by the controller 100, data input/output to/from an external device via the network are interfaced in a page vector format (PDL, PDF, SVG, etc.), and data input/output to/from the scanner 113 and printer 114 are interfaced in a raster data format. Image data in the page vector format input from the external device is interpreted to primitive objects by the CPU 102 to be converted into intermediate data called DL (DisplayList), and the intermediate data is input to the RIP 115.
Since these image data are temporarily stored in the system memory 104 in the controller 100, many kinds of data such as raster data, page vector data (PDL, etc.), DL data, and the like exist on the system memory 104.
The HDD 107 stores image data input from the scanner 113 and raster image data rendered by the RIP 115 as image data.
Of image data to be handled by this MFP, bitmap image data has a large data size. For this reason, the bitmap image data consumes many system resources such as the memory size of the system memory 104, the bandwidth among the general-purpose bus 105, HDDCont 106, and HDD 107, and the like. The processing speed of the system demanded by the user is increasing year by year, and system resources required to meet such demands are ballooning.
Hence, an image compressor/decompressor is prepared in the image processing unit 112 or the RIP 115, and image compression processing such as JPEG or the like is applied to raster image data input from the scanner 113 and bitmap image data described in PDL data. In this way, a system which reduces the load on the system resources is proposed (for example, Japanese Patent Laid-Open No. 11-224331).
Meanwhile, users recently require higher image quality of output images. As one of solutions to such requirements, a high-resolution technology (high-image quality technology) for image data has been promoted. When the aforementioned image compression processing such as JPEG or the like is applied to such high-quality image data to suppress the load cost on the system resources, deterioration of image quality occurs. For this reason, improvement of a compression ratio by the image compression processing and the high-image quality technology normally have a tradeoff relationship. Hence, it is required to suitably attain these two objects at the same time.
Vector conversion for converting a scan image (raster image) into a vector image (image data in the vector format) is one method of solving this problem. For example, a raster image/vector image conversion processing unit is incorporated in the image processing unit 112 in the prior art shown in FIG. 2 to convert a raster image into a vector image.
With this vector conversion, a raster image scanned by the scanner is processed so that a text part is converted into character codes or outline data, straight lines and curves of a thin line image, illustration, and the like are converted into functions, and a table and the like are processed as table data. Hence, high image quality can be attained in text and thin line reproduction.
Since image data is converted into codes or functions, the file size to be stored becomes very small. Upon executing a data transmission function, the time required for transmission can be shortened since the file size is small. In addition, the load on the system resources is reduced.
A system in which the image processing unit 112 incorporates the raster image/vector image conversion processing unit can contribute to a data size reduction and high image quality of a scan image, but it does not provide any contribution to image data received from the network 111. Normally, image data received from the network 111 is image data in the vector format, which includes data obtained by pasting an image separately scanned by a scanner by an image processing application on a terminal such as a personal computer or the like. An image of such type is the same as a raster image, since its entity is not converted into character codes or functions, although it is called image data in the vector format.
Some types of picture drawing applications output a bitmap (raster) image by converting objects (text, image, and the like). For these images, a method of reducing the system resources as in a scan image remains as a problem.